As illustrated in FIG. 1, the humerus 100 of the upper arm is part of a “ball and socket” joint at the shoulder 102. The proximal humerus 102 includes a large rounded humeral head 106 joined to the humerus shaft 116 by a humeral neck 108 and two eminences, the greater and lesser tuberosities 110, 112.
Proximal humeral fractures are the most common humeral fractures. These are often found in patients who have fallen on their arms, creating an axial load on the humerus 100 that causes a fracture of the humeral head 106. In a two-part fracture, the humeral head 106 or a single portion of the head is broken from the humeral shaft 116. In more severe fractures, the humeral head 106 tends to fracture from one or both of the tuberosities 110, 112. As illustrated in FIG. 1, upon occurrence of a fracture the muscles 104 attached to the tuberosities 110, 112 and the humeral shaft 116 pull the humeral head 106, tuberosities 110, 112, and humeral shaft 116 in the directions indicated and away from the correct anatomical positions.
To repair a complex fracture such as illustrated in FIG. 1, a separate reduction device is used to position and retain one or more of the humeral head 106, tuberosities 110, 112, and humeral shaft 116 in the correct anatomical position. As used herein, “reduce” or “reduction” refers to positioning a bone fragment to an anatomically optimal position.
The humeral head 106, tuberosities 110, 112, and humeral shaft 116 are then secured using conventional techniques such as external fixation, percutaneous pinning, plating, intramedullary nailing, shoulder arthroplasty, and others. These methods, however, are not entirely suitable for treatment of more complex fractures, or when tissues are weakened by disease. In these cases, surgical replacement of the shoulder joint is often required.
U.S. Pat. No. 5,472,444 (Huebner et al.) discloses use of a humeral nail for fixation of proximal humeral fractures. Huebner provides an elongated tapered nail or rod having an elongated body with a curved tapered shank that may be secured within a proximal portion of the humeral shaft, with a contiguous proximal portion of the nail extending proximally from the shank to provide a solid foundation to which the humeral head fragments may be secured. The proximal portion has transverse holes oriented at selected angles to receive fasteners attached to the fragments. Huebner does not, however, provide a mechanism to reduce the fracture and retain the fragments during fixation. Also, if a screw is not accurately located in the fragment, Huebner does not provide a mechanism to adjust the location of the fragment relative to the humeral head.